A prior arrangement for testing electric samples is described in GE-OS 23 60 801. In this arrangement, a plate is provided which serves as a carrier for a plurality of testing tips which are fixed in the carrier and are spaced from each other in a predetermined distance. For testing a sample, this testing head can be brought into agreement with the respective probe contact points of the sample. So as to ensure a relatively flexible applicability of such a testing arrangement, this plate with the testing pins can be made larger than the samples, but only under the condition that the distance pattern of the testing tips corresponds to the distance pattern of the probe contact points on the sample. It is furthermore necessary that upon testing the position coordinates of the sample on the contacting tips are determined and that subsequently the control applies the necessary testing voltages to the individual contacting points. Via a computer the testing program, which is in general determined for each sample, is carried out. In order to determine the correct position of the probe contact points, a decoding matrix is provided by means of which the contact points and the testing tips are addressed. If the surface of the plate with the testing tips provided therein, is quite large, the application is relatively flexible as long as the contact pattern between the testing head and sample is in agreement. When these conditions are altered, which is the case in present day practical application in view of the increasing tendency towards continuously rising packing density of the integrated circuit elements and assemblies, the entire plate with its contacting tips is no longer usable. A testing head arrangement adapted to a different spacing has to be prepared. This obviously involves considerable effort.
Another way of selecting the testing pins contacting the probe contact points is described in the IBM Technical Disclosure Bulletin Vol. 17, No. 2, July, 1974, pages 459 and 460. According thereto, the testing head consists of two parts where in the upper part pins are resiliently supported and in the lower part the testing pins are arranged in the same distance and pattern as in the upper part. Between the upper and the lower part, a mask is inserted having holes which correspond to the distance and pattern of the probe contact points to be contacted. When the two parts are joined together, with the mask being included, only those testing pins touch the contacts which are actuated by the pins that protrude through apertures in the mask. This arrangement is suitable particularly for use in testing printed circuit cards. If the pattern of the card as a whole is changed, for instance through a change, if only partly, of the distances of the probe contact points, which then no longer correspond to the distances of the testing pins and the operating pins, the entire testing unit or the entire testing head, respectively, is no longer usable.